Hygrocybe griseonigricans C.Q. Wang & T.H. Li, 2020

Wang, Chao-Qun, Zhang, Ming & Li, Tai-Hui, 2020, Three new species from Guangdong Province of China, and a molecular assessment of Hygrocybe subsection Hygrocybe, MycoKeys 75, pp. 145-161 : 145

Hygrocybe griseonigricans C.Q. Wang & T.H. Li sp. nov. Figures 3C, D , 5

Typification.

China. Guangdong Province, Nanxiong City, Qingzhang Mountain, elev. ca. 340 m, 15 May 2018, M. Zhang & X.N. Chen (GDGM73527, holotype!).

Sequences ex holotype.

MW001790 (ITS), MW007883 (LSU).

Etymology.

" griseo -": gray, "- nigricans ": black. The species epithet " Hygrocybe griseonigricans " refers to its gray pileus with obvious blackening reaction.

Diagnosis.

Hygrocybe griseonigricans differs from H. astatogala by having a duller pilus color, variable (subglobose to elongate) basidiopore shapes, 1-, 2- and 4-spored basidia and differences in molecular sequences.

Description.

Pileus 25-70 mm diam., broad conical to umbonate disc when young, expanded to umbonate, convex, even to almost plane when mature, white, pale yellow (3A3) to dull yellow (3B3), densely covered with radially arranged black hairy fibrils with appressed or uplifted ends on surface, nigrescent when bruised or mature; margin incurved when young, expanded to straight when mature. Lamellae free, white at first, turning black when bruised or mature, up to 7 mm wide, waxy, fragile, with 1-3 lamelluate between two entire lamellae, edge usually eroded. Stipe 50-150 × 5-12 mm, central, cylindrical, sometimes slightly curve, usually wider at base, hollow, white to yellow at the upper part, usually white at the base, changing to black with age or when bruised, covered with clustered black longitudinal fibrils.

Basidiospores 9-10.5 × (6)6.5-9.5(10) μm [mean length = 9.7 μm, mean width = 8 μm], Q = (0.95)1.1-1.6, Qm = 1.23, globose, subglobose to broadly ovoid, smooth, thin-walled. Basidia 32-44.5 × 8-11.5 μm, 1-, 2- or 4-spored, clavate, with sterigmata up to 10 μm long, sterigmata of 2-spored basidia usually longer than those of 4-spored basidia. Pileipellis a cutis or trichoderm, hyphae 2-15 μm in diam. Hymenophoral trama regular, hyphae 2.5-21 μm broad, translucent, mainly thin-walled rarely thick-walled.

Habit, habitat and distribution.

Solitary to scattered on soil; basidiomata occurring from April to September. So far known from Southern China.

Additional specimens examined.

China. Guangdong Province, Nanxiong City, Qingzhang Mountain, elev. ca. 340 m, 15 May 2018, M. Zhang & X.N. Chen (GDGM73528); Renhua County, Danxia Mountain, elev. ca. 100 m, 12 June 2020, M. Zhang & L.Q. Wu (GDGM81385).

Remarks.

The distinctive morphological features of Hygrocybe griseonigricans are the following: white to dull yellow-colored pileus with black discoloration, white lamellae, white stipe base, and variable basidiospore shapes, from globose, subglobose to broadly ovoid. The ITS and LSU phylogenetic analyses support H. griseonigricans as a distinct species within a well-supported clade that includes H. astatogala (Figs 1 - 2 ).

Hygrocybe conica , originally described from Germany, is similar to H. griseonigricans . However, H. conica has a larger (up to 100 mm diameter) and somewhat fibrillose pileus, and usually grayish lamellae ( Boertmann 2010). Hygrocybe astatogala , originally described from Madagascar, resembles H. griseonigricans in the black fibrils on the pileus. However, H. astatogala , has distinct and persistent conical and yellow to orange pileus, yellow to orange lamellae, and subglobose to ovoid basidiospores ( Horak 1990; Leelavathy et al. 2006).

Figures

Figure 1. Maximum Likelihood phylogram of genus Hygrocybe based on LSU matrix, rooted with Hygroaster albellus (EF 551314), H. nodulisporus (EF 561625) and H. andersonii (KF 291171). The newly generated sequences in this study are showed in bold. GenBank accession numbers of downloaded sequences or voucher numbers of new sequences are given after the species names. Bootstrap values more than 50 % are shown around the branches.

Figure 2. Maximum-likelihood tree of sect. Hygrocybe based on ITS matrix, rooted with members of subsect. Macrosporae. The newly generated sequences in this study are indicated in bold face. GenBank accession number of downloaded sequence or voucher number of newly generated sequence and place of origin are given after the species name of each sequence. Bootstrap values more than 50 % are shown around the branches.

Figure 3. Basidiomes of Hygrocybe species A Hygrocybe debilipes (GDGM 59314) B Hygrocybe debilipes (GDGM 57013) C Hygrocybe griseonigricans (GDGM 73527) D Hygrocybe griseonigricans (GDGM 81394) E Hygrocybe rubroconica (GDGM 45213) F Hygrocybe rubroconica (GDGM 45214).

Figure 5. Microscopic features Hygrocybe griseonigricans (GDGM 73527) A basidiospores B basidia C terminal cells of hymenophoral trama D terminal cells of pileipellis.